AM5 PCIe lane sharing refers to how multiple devices share the available lanes in an AM5 PCIe slot.
AM5 PCIe lane sharing refers to how multiple devices share the available lanes in an AM5 PCIe slot.
Setting up a fresh system is taking some time, and I'm feeling a bit disappointed with the current motherboard options. The PCIe lane sharing is really limiting my plans—my goal is to use two M.2 drives in RAID 0 for the operating system and another two for scratch space. It looks like most boards I've seen are sharing lanes, which means using all four M.2 slots halves the bandwidth to the GPU. The only model that seems to handle this better is the Asus Proart X670E Creator Wifi, as it doesn't share lanes except for the third PCIe slot and the third M.2, which I can manage since I won't be using PCIe 3. The rest are problematic because any M.2 slot could disrupt GPU performance. This architecture feels subpar. Anyone have recommendations for boards with better lane sharing? I usually go for Asus but need alternatives right now since the Proart is out of stock everywhere.
You should use SSDs for raids because they improve performance and reliability. Mirroring works well with NVMe but not with SATA mirrors. Consumer boards aren't typically raided, which is the right approach. They're offering extra space by including a 4yh slot. They're trying to convince you it will reduce GPU load, so you can weigh the pros and cons carefully. If you require four drives, consider a server instead.
It's likely due to USB4 taking up four of the CPU's eight lanes for M.2 use. The X670E faced more trouble because USB4 was required. Boards with mainly 4.0 M.2 slots, such as the Nova, don't encounter this issue. MSI lets you turn off lane sharing with USB4 ports (e.g., X870E Tomahawk), though it also turns them off.
Still struggling to locate the proart x670e. Also discovered the tomahawk is solid, but it seems raids aren't possible on a CPU M.2. Only chipset M.2 drives are suitable for raiding. Feeling stuck again. I think I'll stick with a single Gen 5 M.2 for the OS and set up a raid 1 for data, keeping a spare M.2 for other needs. Yeah, a thread-ripper would fix everything, but winning the lottery would make it worth it!
I don't have insight into your workloads, but halving the PCIe lanes on a GPU will likely have minimal impact even with a 5090 PCIe 4 x 8 setup. The Asus X870E Hero can run on 5 NVMe drives using various configurations. If you prefer not to split lanes, you can still use a single PCIe 5 x 2 or two PCIe 4 x 8 connection.
I was running version 5 on my X670E-F. I moved it from my lower bay to another PC, but now only four drives remain. I didn’t enable lane sharing and chose the -F option instead, which cost more back then. Edit: I stopped using SATA altogether and turned it off. I haven’t touched it since 2020 when I switched to AM4 and NVMe.